Method for rapidly detecting main components of dry powder extinguishing agent

Abstract

The invention belongs to the field of fire extinguishing agent component detection, and particularly relates to a method for rapidly detecting main components of a dry powder fire extinguishing agent. According to the method, an XRF fluorescence detection method and an ultraviolet spectrophotometric method are combined, the relation between the screening value and the main components in the fire extinguishing agent is creatively determined, the fire extinguishing agent can be rapidly detected to judge whether the quality of the fire extinguishing agent is qualified or not, and a new thought is provided for detection of the dry powder fire extinguishing agent; obviously adulterated samples can be distinguished within the detection time of 120 seconds, the first component of the dry powder extinguishing agent can be quantified by the rapid quantification method only needing about 30 minutes of pretreatment and color development time, compared with a traditional national standard method needing more than 5 hours of detection time, the detection efficiency is greatly improved, the experiment condition requirement is low, and the method is suitable for large-scale popularization and application. The method has the advantages of high sensitivity, good accuracy, excellent selectivity, environment-friendly reagent, fast and accurate detection result, realization of spot check on spot check site, and suitableness for various scenes.

Description

Technical Field

[0001] The invention belongs to the field of fire extinguishing agent component detection, and in particular relates to a method for quickly detecting the main components of a dry powder fire extinguishing agent. Background Art

[0002] Dry powder fire extinguishing agent is a dry and easy-flowing fine powder used for fire extinguishing. It is composed of inorganic salts with fire extinguishing efficiency (main ingredient) and a small amount of additives that are dried, crushed and mixed into fine solid powder. It is generally divided into two categories: BC dry powder fire extinguishing agent (sodium bicarbonate) and ABC dry powder (ammonium phosphate salt).

[0003] The main reason why dry powder fire extinguishing agents can extinguish fires lies in their main ingredients. The specific principles are as follows: (1) Inhibiting chemical reactions: The main ingredients in dry powder fire extinguishing agents can react with the chemical substances in the flame to inhibit the chemical reaction process of the flame; (2) Absorbing heat and cooling: The main ingredients in dry powder fire extinguishing agents have a high heat absorption capacity and can quickly absorb the heat around the flame, lowering the temperature of the flame, making the flame lose the conditions for continuing to burn and causing the flame to go out; (3) Preventing the spread of flames: Dry powder fire extinguishing agents form a dust layer composed of the main ingredients and auxiliary ingredients on the fire source. This dust layer can effectively prevent the spread of flames; (5) Reducing the combustion rate: The main ingredients in dry powder fire extinguishing agents can react with the combustible substances in the flame to generate inert substances, reducing the combustion rate and slowing the spread of the fire.

[0004] The content of the main components in the dry powder fire extinguishing agent has become the main factor to measure whether the dry powder fire extinguishing agent is qualified. The traditional national standard method often uses the quinoline method for determination, which is to mix the phosphorus solution to be tested with a certain amount of quinoline solution and react for a certain time under acidic conditions. During the reaction, the phosphate ion and quinoline react chemically to form a yellow complex, and then the reaction product is separated by filter paper or other appropriate methods to obtain a solid containing the complex; finally, by weighing the mass change of the dried complex, the mass of the phosphate ion can be calculated, thereby determining the content of diammonium phosphate. However, this method takes too long to detect, often requiring more than 5 hours of detection time, and is not suitable for rapid detection on site. Therefore, how to quickly and accurately detect the dry powder fire extinguishing agent on site, which has become a problem that needs to be solved in this field. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a method for quickly detecting the main components of a dry powder fire extinguishing agent. After determining the screening value, further detection is performed according to the screening value, so that the content of the main components in the dry powder fire extinguishing agent can be detected, and its content can be quickly detected on site to quickly determine whether the fire extinguishing agent is qualified, thereby solving the problem that the main components in the dry powder fire extinguishing agent cannot be quickly and accurately detected to determine the quality of the fire extinguishing agent.

[0006] The technical solution of the present invention is as follows:

[0007] The present invention provides a method for rapid detection of main components of a dry powder fire extinguishing agent, comprising the following steps:

[0008] S1, the fire extinguishing agent samples are tested by XRF fluorescence detection method, and those below the screening value are judged as unqualified samples;

[0009] The screening value is denoted as V, and the calculation method is as follows:

[0010] V = MK × R / S × 100%;

[0011] R = M + (0.75 + 2.5 × M)%;

[0012] Wherein, M takes the minimum value of the first main component content published in GB 4066-2017, M is 75%;

[0013] S is the content of all main components, S is taken as 90%;

[0014] R is the content of any main component;

[0015] K is the correction coefficient, K = 0.116;

[0016] S2, use ultraviolet spectrophotometry to detect samples greater than or equal to the screening value. If the test value is lower than 75%, it is judged as an unqualified sample; if the test value is greater than or equal to 75%, it is judged as a qualified sample.

[0017] The detection method process is as follows Figure 1 shown.

[0018] Preferably, in S1, the fire extinguishing agent sample is mixed, and the specific processing method is as follows:

[0019] S11, preparation: conduct a safety check on the dry powder fire extinguishing agent and prepare a clean container to collect the sprayed dry powder fire extinguishing agent, then pull out the safety pin and point the nozzle of the fire extinguisher to a safe area;

[0020] S12, spray dry powder fire extinguishing agent: press the pressure handle of the fire extinguisher to spray the dry powder fire extinguishing agent into the prepared container;

[0021] S13, collect samples: quickly move the container to a safe area, seal the container, let it stand, and then mix the sample thoroughly to obtain a mixed sample.

[0022] The standing time is 15 min.

[0023] Preferably, in S1, the detection steps of the XRF fluorescence detection method are as follows:

[0024] (1) Establishment of standard curve: Weigh 2 g, 4 g, 6 g, 8 g, 10 g, 12 g, and 15 g of ammonium dihydrogen phosphate, respectively, mix with 18 g, 16 g, 14 g, 12 g, 10 g, 8 g, and 5 g of silicon dioxide, and grind with a quartz mortar to form 20 g of uniform standard samples. The contents of ammonium dihydrogen phosphate in the standard samples are 10%, 20%, 30%, 40%, 50%, 60%, and 75%, respectively;

[0025] Preheat the instrument to make it stable, set the tube pressure, tube flow, working parameters, etc. of the instrument according to the recommended parameters of the XRF spectrometer, place the prepared standard sample on the measurement window, measure the fluorescence intensity of phosphorus element of each standard sample under the specified operating conditions, and draw a working curve with the phosphorus content of the standard sample as the ordinate and the phosphorus element X-ray fluorescence intensity (Icps) of the measured standard sample as the abscissa;

[0026] (2) Sample preparation: Place the mixed sample into a sample cup, compact it with a quartz rod, and set aside;

[0027] (3) Sample measurement: The X-ray fluorescence intensity of phosphorus was measured under the same analytical conditions as the calibration curve.

[0028] The test results of the samples are expressed as follows:

[0029] The X-ray fluorescence intensity (Icps) of phosphorus in the sample is measured experimentally, and the corresponding phosphorus content is obtained through the standard curve. The content of diammonium phosphate in the sample is obtained through the conversion coefficient. The content of diammonium phosphate is calculated according to formula (1):

[0030]

[0031] In the formula,

[0032] w1——mass fraction of diammonium phosphate, %;

[0033] w——phosphorus content of the sample, %;

[0034] 30.97 – molar mass of phosphorus, g / mol;

[0035] 115.028 – The molar mass of diammonium phosphate, g / mol.

[0036] Preferably, in S2, the steps of ultraviolet spectrophotometry detection are as follows:

[0037] A. Establishment of standard curve: Pipette 0.0mL, 0.25mL, 0.5mL, 1.0mL, 1.5mL, 2.0mL, and 2.5mL of phosphorus standard solution into 7 100mL volumetric flasks, add water to make up to 100mL. The phosphorus concentrations in the 7 standard curve solutions are 0.0mg / L, 0.05mg / L, 0.10mg / L, 0.20mg / L, 0.30mg / L, 0.40mg / L, and 0.50mg / L respectively;

[0038] B. Color determination: add 2 mL of molybdate solution and 1 mL of ascorbic acid solution to the standard curve solution, color develop for 15 min at room temperature (20-25°C), use water as a reference, use a 30 mm pathlength cuvette to measure the absorbance at 720 nm, and complete the measurement within 30 min; the absorbance value after deducting the blank test is the ordinate, and the phosphorus concentration (mg / L) is the abscissa, and the standard curve is drawn;

[0039] C. Sample solution preparation: weigh about 0.1g (accurate to 0.01g) of dry powder fire extinguishing agent sample, place it in a quartz mortar and add 2mL of acetone, stirring continuously to remove the silicon film on the surface of the fire extinguishing agent powder; after the acetone evaporates and dries, add 5-10mL of water (60-70°C) to dissolve and filter, wash the insoluble matter on the filter paper with 25mL of water 3-5 times, collect the filtrate and washing liquid in a 50mL volumetric flask, and then make up to volume with water; take 0.1mL from the above liquid and dilute it to the scale line in a colorimetric tube with water, which is the sample solution to be tested;

[0040] D. Sample solution determination: Add 2 mL of ammonium molybdate solution and 1 mL of ascorbic acid solution to the solution to be tested. After color development for 15 minutes at room temperature, use water as a reference and use a 30 mm pathlength cuvette to determine the absorbance value at a wavelength of 720 nm. The measurement should be completed within 30 minutes.

[0041] The results of the sample solution are expressed as follows:

[0042] The content of diammonium phosphate is calculated according to formula (2):

[0043]

[0044] Where:

[0045] w1——mass fraction of diammonium phosphate, %;

[0046] A——absorbance of sample solution;

[0047] A0——absorbance value of blank sample;

[0048] a——intercept of the standard curve;

[0049] b——the slope of the standard curve;

[0050] m——mass of dry powder fire extinguishing agent sample, g;

[0051] 50——the volume of sample solution, mL;

[0052] 1000——The dilution factor when 0.1mL of sample solution is added to a 100mL colorimetric tube and the volume is fixed;

[0053] 10 -6 ——unit conversion multiple;

[0054] 30.97 – molar mass of phosphorus, g / mol;

[0055] 115.028 – The molar mass of diammonium phosphate, g / mol.

[0056] The present invention obtains a formula for calculating the screening value based on a large number of experiments and data, and determines the correction coefficient through a large number of trials and errors and calculations. The fire extinguishing agent can be accurately measured using this formula.

[0057] The beneficial effects of the present invention are:

[0058] (1) The present invention combines XRF fluorescence detection method with ultraviolet spectrophotometry, and creatively determines the relationship between the screening value in the present invention and the main components in the fire extinguishing agent, so that the fire extinguishing agent can be quickly tested to determine whether its quality is qualified, providing a new idea for the detection of dry powder fire extinguishing agents;

[0059] (2) The present invention can distinguish obviously adulterated samples within a detection time of 120 seconds. The rapid quantitative method only requires about 30 minutes of pretreatment and color development time to quantify the first component of the dry powder fire extinguishing agent. Compared with the traditional national standard method that requires more than 5 hours of detection time, the detection efficiency is greatly improved and the experimental conditions are low. It has high sensitivity, good accuracy, excellent selectivity, and environmentally friendly reagents, ensuring that the test results are fast and accurate, and that on-site sampling and testing can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] Figure 1 The present invention is a flow chart of the detection method. DETAILED DESCRIPTION

[0061] In order to enable those skilled in the art to better understand the present invention, the present invention is further described in conjunction with specific implementation methods.

[0062] Example 1

[0063] Experimental instruments:

[0064] A method for rapid detection of main components of dry powder fire extinguishing agent, comprising the following steps:

[0065] S1, the fire extinguishing agent samples are tested by XRF fluorescence detection method, and those below the screening value are judged as unqualified samples;

[0066] The screening value is denoted as V, and the calculation method is as follows:

[0067] V = MK × R / S × 100%;

[0068] R = M + (0.75 + 2.5 × M)%;

[0069] Wherein, M takes the minimum value of the first main component content published in GB 4066-2017, M is 75%;

[0070] S is the content of all main components, S is taken as 90%;

[0071] R is the content of any main component;

[0072] K is the correction coefficient, K = 0.116;

[0073] The fire extinguishing agent samples were mixed and the specific processing method is as follows:

[0074] Safety check: First make sure the fire extinguisher is in a safe condition with no signs of damage or leakage; check whether the pressure indicator is normal and whether the safety pin is intact.

[0075] Prepare tools: Prepare a clean container to collect the sprayed dry powder fire extinguishing agent. The container should be large enough to hold the required sample volume.

[0076] Remove the safety pin: Remove the safety pin or fuse according to the instructions on the fire extinguisher.

[0077] Point to a safe area: Point the nozzle of the fire extinguisher to a safe, windless or low-wind area to avoid the dry powder being blown away by the wind.

[0078] Short spray: Gently press the pressure handle of the fire extinguisher and perform 5 short sprays to spray a portion of the dry powder fire extinguishing agent into the prepared container. Be careful not to completely release all the dry powder in the fire extinguisher to avoid affecting its future use.

[0079] Collect samples: Move the container to a safe area quickly and seal it to prevent contamination. Let it sit for 15 minutes and then use the “four-part method” to mix the sample evenly.

[0080] Disposal of remaining dry powder: Clean the spraying area and properly dispose of remaining dry powder fire extinguishing agent.

[0081] The detection steps of the XRF fluorescence detection method are as follows:

[0082] (1) Establishment of standard curve: Weigh 2 g, 4 g, 6 g, 8 g, 10 g, 12 g, and 15 g of ammonium dihydrogen phosphate, respectively, mix with 18 g, 16 g, 14 g, 12 g, 10 g, 8 g, and 5 g of silicon dioxide, and grind with a quartz mortar to form 20 g of uniform standard samples. The contents of ammonium dihydrogen phosphate in the standard samples are 10%, 20%, 30%, 40%, 50%, 60%, and 75%, respectively;

[0083] Preheat the instrument to make it stable, set the tube pressure, tube flow, working parameters, etc. of the instrument according to the recommended parameters of the XRF spectrometer, place the prepared standard sample on the measurement window, measure the fluorescence intensity of phosphorus element of each standard sample under the specified operating conditions, and draw a working curve with the phosphorus content of the standard sample as the ordinate and the phosphorus element X-ray fluorescence intensity (Icps) of the measured standard sample as the abscissa;

[0084] In order to facilitate the requirements of rapid on-site testing, the standard curve can be established in the laboratory, and the accuracy of the calibration curve should be verified regularly. The verification frequency is based on the time required by the XRF spectrometer manual or 3 months, whichever is shorter. During verification, a standard substance used in making the calibration curve can be selected, and the deviation analysis between its test results and the standard value or reference value of the standard substance can be performed. When the relative standard deviation is greater than 15%, recalibration is performed until it is qualified.

[0085] (2) Sample preparation: Place the mixed sample into a sample cup, compact it with a quartz rod, and set aside;

[0086] (3) Sample measurement: The X-ray fluorescence intensity of phosphorus was measured under the same analytical conditions as the calibration curve.

[0087] The test results of the samples are expressed as follows:

[0088] The X-ray fluorescence intensity (Icps) of phosphorus in the sample is measured experimentally, and the corresponding phosphorus content is obtained through the standard curve. The content of diammonium phosphate in the sample is obtained through the conversion coefficient. The content of diammonium phosphate is calculated according to formula (1):

[0089]

[0090] In the formula,

[0091] w1——mass fraction of diammonium phosphate, %;

[0092] w——phosphorus content of the sample, %;

[0093] 30.97 – molar mass of phosphorus, g / mol;

[0094] 115.028 – The molar mass of diammonium phosphate, g / mol.

[0095] The calculation result shall be rounded to 3 significant figures.

[0096] Each sample was analyzed in parallel twice, and the average value was calculated.

[0097] S2, use ultraviolet spectrophotometry to detect samples greater than or equal to the screening value. If the test value is lower than 75%, it is judged as an unqualified sample; if the test value is greater than or equal to 75%, it is judged as a qualified sample.

[0098] The steps of the ultraviolet spectrophotometry detection are as follows:

[0099] A. Establishment of standard curve: Pipette 0.0mL, 0.25mL, 0.5mL, 1.0mL, 1.5mL, 2.0mL, and 2.5mL of phosphorus standard solution into 7 100mL volumetric flasks, add water to make up to 100mL. The phosphorus concentrations in the 7 standard curve solutions are 0.0mg / L, 0.05mg / L, 0.10mg / L, 0.20mg / L, 0.30mg / L, 0.40mg / L, and 0.50mg / L respectively;

[0100] B. Color determination: add 2 mL of molybdate solution and 1 mL of ascorbic acid solution to the standard curve solution, color develop for 15 min at room temperature (20-25°C), use water as a reference, use a 30 mm pathlength cuvette to measure the absorbance at 720 nm, and complete the measurement within 30 min; the absorbance value after deducting the blank test is the ordinate, and the phosphorus concentration (mg / L) is the abscissa, and the standard curve is drawn;

[0101] To facilitate the requirements of rapid on-site testing, a standard curve can be established in the laboratory. To ensure the measurement quality, each batch of samples should have an intermediate calibration point, and the relative error between the measured value of the intermediate calibration point and the concentration of the corresponding point on the standard curve should not exceed 10%;

[0102] C. Sample solution preparation: weigh about 0.1g (accurate to 0.01g) of dry powder fire extinguishing agent sample, place it in a quartz mortar and add 2mL of acetone, stirring continuously to remove the silicon film on the surface of the fire extinguishing agent powder; after the acetone evaporates and dries, add 5-10mL of water (60-70℃) to dissolve and filter, wash the insoluble matter on the filter paper with about 25mL of water 3-5 times, collect the filtrate and washing liquid in a 50mL volumetric flask, and then make up to volume with water; take 0.1mL from the above liquid and dilute it to the scale line in a colorimetric tube with water, which is the sample solution to be tested;

[0103] D. Sample solution determination: Add 2 mL of ammonium molybdate solution and 1 mL of ascorbic acid solution to the solution to be tested. After color development for 15 minutes at room temperature, use water as a reference and use a 30 mm pathlength cuvette to determine the absorbance value at a wavelength of 720 nm. The measurement should be completed within 30 minutes.

[0104] The results of the sample solution are expressed as follows:

[0105] The content of diammonium phosphate is calculated according to formula (2):

[0106]

[0107] Where:

[0108] w1——mass fraction of diammonium phosphate, %;

[0109] A——absorbance of sample solution;

[0110] A0——absorbance value of blank sample;

[0111] a——intercept of the standard curve;

[0112] b——the slope of the standard curve;

[0113] m——mass of dry powder fire extinguishing agent sample, g;

[0114] 50——the volume of sample solution, mL;

[0115] 1000——The dilution factor when 0.1mL of sample solution is added to a 100mL colorimetric tube and the volume is fixed;

[0116] 10 -6 ——unit conversion multiple;

[0117] 30.97 – molar mass of phosphorus, g / mol;

[0118] 115.028 – The molar mass of diammonium phosphate, g / mol.

[0119] The calculation result shall be rounded to 3 significant figures.

[0120] Each sample was analyzed in parallel twice, and the average value was calculated.

[0121] Six commercially available dry powder fire extinguishing agent products were selected, and two samples of the same amount were taken from each product. The traditional national standard method and the above method were used for determination, respectively. The results are shown in Table 1:

[0122] Table 1 Comparison of content detected by this embodiment and national standard method

[0123]

[0124] Its detection time and other parameters are shown in Table 2:

[0125] Table 2 Comparison between this embodiment and national standard method

[0126]

[0127] It can be seen from Table 1 that the content determined by the method of this embodiment is not much different from that determined by the national standard method. However, it can be seen from Table 2 that the detection method of this embodiment has high accuracy and fast detection speed, and can be used as a detection method for the main components of dry powder fire extinguishing agent, and can be used as a detection method for on-site sampling and testing.

Claims

1. A method for rapid detection of the main components of a dry powder fire extinguishing agent, characterized in that: The following steps are involved: S1, the fire extinguishing agent samples are tested by XRF fluorescence detection method, and those below the screening value are judged as unqualified samples; The screening value is denoted as V, and the calculation method is as follows: V = MK × R / S × 100%; R= M+(0.75+2.5×M)%; Wherein, M takes the minimum value of the first main component content published in GB 4066-2017, M is 75%; S is the content of all main components, S is taken as 90%; R is the content of any main component; K is the correction coefficient, K=0.116; S2, use ultraviolet spectrophotometry to detect samples greater than or equal to the screening value. If the test value is lower than 75%, it is judged as an unqualified sample; if the test value is greater than or equal to 75%, it is judged as a qualified sample.

2. The method according to claim 1, characterized in that In S1, the fire extinguishing agent sample is mixed and the specific processing method is as follows: S11, preparation: conduct a safety check on the dry powder fire extinguishing agent and prepare a clean container to collect the sprayed dry powder fire extinguishing agent, then pull out the safety pin and point the nozzle of the fire extinguisher to a safe area; S12, spray dry powder fire extinguishing agent: press the pressure handle of the fire extinguisher to spray the dry powder fire extinguishing agent into the prepared container; S13, collect samples: quickly move the container to a safe area, seal the container, let it stand, and then mix the sample thoroughly to obtain a mixed sample.

3. The method according to claim 2, characterized in that In S13, the standing time is 15 min.

4. The method according to claim 1, characterized in that In S1, the detection steps of the XRF fluorescence detection method are as follows: (1) Establishment of standard curve: Weigh 2 g, 4 g, 6 g, 8 g, 10 g, 12 g, and 15 g of ammonium dihydrogen phosphate, respectively, mix with 18 g, 16 g, 14 g, 12 g, 10 g, 8 g, and 5 g of silicon dioxide, and grind in a quartz mortar to form a 20 g uniform standard sample; Preheat the instrument to make it stable, set the tube pressure, tube flow, working parameters, etc. of the instrument according to the recommended parameters of the XRF spectrometer, place the prepared standard sample on the measurement window, measure the fluorescence intensity of phosphorus element of each standard sample under the specified operating conditions, and draw the working curve with the phosphorus content of the standard sample as the ordinate and the phosphorus element X-ray fluorescence intensity (Icps) of the measured standard sample as the abscissa; (2) Sample preparation: Place the mixed sample into a sample cup, compact it with a quartz rod, and set aside; (3) Sample determination: The X-ray fluorescence intensity of phosphorus was determined under the same analytical conditions as the calibration curve.

5. The method according to claim 4, characterized in that (1), the contents of diammonium phosphate in the standard samples were 10%, 20%, 30%, 40%, 50%, 60% and 75%, respectively.

6. The method according to claim 1, characterized in that In S2, the steps of ultraviolet spectrophotometry detection are as follows: A. Establishment of standard curve: pipette 0.0 mL, 0.25 mL, 0.5 mL, 1.0 mL, 1.5 mL, 2.0 mL, and 2.5 mL of phosphorus standard solution into seven 100 mL volumetric flasks, and add water to make up to 100 mL; B. Color determination: add 2 mL of molybdate solution and 1 mL of ascorbic acid solution to the standard curve solution, color develop for 15 min at room temperature, and use water as a reference. Use a 30 mm pathlength cuvette to measure the absorbance at 720 nm. The measurement should be completed within 30 min. The absorbance after deducting the blank test is the ordinate, and the phosphorus concentration mg / L is the abscissa to draw the standard curve. C. Sample preparation: Weigh 0.1 g of dry powder fire extinguishing agent sample, place it in a quartz mortar and add 2 mL of acetone, stirring continuously to remove the silicon film on the surface of the fire extinguishing agent powder; After the acetone evaporates, add 5-10 mL of water to dissolve and filter, wash the insoluble matter on the filter paper with 25 mL of water 3-5 times, collect the filtrate and washing liquid in a 50 mL volumetric flask, and then make up to volume with water; take 0.1 mL of the above liquid into a colorimetric tube and dilute it to the scale line with water, which is the sample solution to be tested; D. Sample solution determination: Add 2 mL of ammonium molybdate solution and 1 mL of ascorbic acid solution to the solution to be tested. After color development for 15 minutes at room temperature, use water as a reference and use a 30 mm pathlength cuvette to determine the absorbance value at a wavelength of 720 nm. The measurement should be completed within 30 minutes.

7. The method according to claim 6, characterized in that In A, the phosphorus concentrations in the 7 standard curve solutions are 0.0 mg / L, 0.05 mg / L, 0.10 mg / L, 0.20 mg / L, 0.30 mg / L, 0.40 mg / L, and 0.50 mg / L, respectively.

8. The method according to claim 6, characterized in that In B, the room temperature is 20-25°C.

Images